1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * fs/proc/kcore.c kernel ELF core dumper
4 *
5 * Modelled on fs/exec.c:aout_core_dump()
6 * Jeremy Fitzhardinge <jeremy@sw.oz.au>
7 * ELF version written by David Howells <David.Howells@nexor.co.uk>
8 * Modified and incorporated into 2.3.x by Tigran Aivazian <tigran@veritas.com>
9 * Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@veritas.com>
10 * Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com>
11 */
12
13 #include <linux/crash_core.h>
14 #include <linux/mm.h>
15 #include <linux/proc_fs.h>
16 #include <linux/kcore.h>
17 #include <linux/user.h>
18 #include <linux/capability.h>
19 #include <linux/elf.h>
20 #include <linux/elfcore.h>
21 #include <linux/notifier.h>
22 #include <linux/vmalloc.h>
23 #include <linux/highmem.h>
24 #include <linux/printk.h>
25 #include <linux/memblock.h>
26 #include <linux/init.h>
27 #include <linux/slab.h>
28 #include <linux/uaccess.h>
29 #include <asm/io.h>
30 #include <linux/list.h>
31 #include <linux/ioport.h>
32 #include <linux/memory.h>
33 #include <linux/sched/task.h>
34 #include <linux/security.h>
35 #include <asm/sections.h>
36 #include "internal.h"
37
38 #define CORE_STR "CORE"
39
40 #ifndef ELF_CORE_EFLAGS
41 #define ELF_CORE_EFLAGS 0
42 #endif
43
44 static struct proc_dir_entry *proc_root_kcore;
45
46
47 #ifndef kc_vaddr_to_offset
48 #define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
49 #endif
50 #ifndef kc_offset_to_vaddr
51 #define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
52 #endif
53
54 static LIST_HEAD(kclist_head);
55 static DECLARE_RWSEM(kclist_lock);
56 static int kcore_need_update = 1;
57
58 /*
59 * Returns > 0 for RAM pages, 0 for non-RAM pages, < 0 on error
60 * Same as oldmem_pfn_is_ram in vmcore
61 */
62 static int (*mem_pfn_is_ram)(unsigned long pfn);
63
register_mem_pfn_is_ram(int (* fn)(unsigned long pfn))64 int __init register_mem_pfn_is_ram(int (*fn)(unsigned long pfn))
65 {
66 if (mem_pfn_is_ram)
67 return -EBUSY;
68 mem_pfn_is_ram = fn;
69 return 0;
70 }
71
pfn_is_ram(unsigned long pfn)72 static int pfn_is_ram(unsigned long pfn)
73 {
74 if (mem_pfn_is_ram)
75 return mem_pfn_is_ram(pfn);
76 else
77 return 1;
78 }
79
80 /* This doesn't grab kclist_lock, so it should only be used at init time. */
kclist_add(struct kcore_list * new,void * addr,size_t size,int type)81 void __init kclist_add(struct kcore_list *new, void *addr, size_t size,
82 int type)
83 {
84 new->addr = (unsigned long)addr;
85 new->size = size;
86 new->type = type;
87
88 list_add_tail(&new->list, &kclist_head);
89 }
90
get_kcore_size(int * nphdr,size_t * phdrs_len,size_t * notes_len,size_t * data_offset)91 static size_t get_kcore_size(int *nphdr, size_t *phdrs_len, size_t *notes_len,
92 size_t *data_offset)
93 {
94 size_t try, size;
95 struct kcore_list *m;
96
97 *nphdr = 1; /* PT_NOTE */
98 size = 0;
99
100 list_for_each_entry(m, &kclist_head, list) {
101 try = kc_vaddr_to_offset((size_t)m->addr + m->size);
102 if (try > size)
103 size = try;
104 *nphdr = *nphdr + 1;
105 }
106
107 *phdrs_len = *nphdr * sizeof(struct elf_phdr);
108 *notes_len = (4 * sizeof(struct elf_note) +
109 3 * ALIGN(sizeof(CORE_STR), 4) +
110 VMCOREINFO_NOTE_NAME_BYTES +
111 ALIGN(sizeof(struct elf_prstatus), 4) +
112 ALIGN(sizeof(struct elf_prpsinfo), 4) +
113 ALIGN(arch_task_struct_size, 4) +
114 ALIGN(vmcoreinfo_size, 4));
115 *data_offset = PAGE_ALIGN(sizeof(struct elfhdr) + *phdrs_len +
116 *notes_len);
117 return *data_offset + size;
118 }
119
120 #ifdef CONFIG_HIGHMEM
121 /*
122 * If no highmem, we can assume [0...max_low_pfn) continuous range of memory
123 * because memory hole is not as big as !HIGHMEM case.
124 * (HIGHMEM is special because part of memory is _invisible_ from the kernel.)
125 */
kcore_ram_list(struct list_head * head)126 static int kcore_ram_list(struct list_head *head)
127 {
128 struct kcore_list *ent;
129
130 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
131 if (!ent)
132 return -ENOMEM;
133 ent->addr = (unsigned long)__va(0);
134 ent->size = max_low_pfn << PAGE_SHIFT;
135 ent->type = KCORE_RAM;
136 list_add(&ent->list, head);
137 return 0;
138 }
139
140 #else /* !CONFIG_HIGHMEM */
141
142 #ifdef CONFIG_SPARSEMEM_VMEMMAP
143 /* calculate vmemmap's address from given system ram pfn and register it */
144 static int
get_sparsemem_vmemmap_info(struct kcore_list * ent,struct list_head * head)145 get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
146 {
147 unsigned long pfn = __pa(ent->addr) >> PAGE_SHIFT;
148 unsigned long nr_pages = ent->size >> PAGE_SHIFT;
149 unsigned long start, end;
150 struct kcore_list *vmm, *tmp;
151
152
153 start = ((unsigned long)pfn_to_page(pfn)) & PAGE_MASK;
154 end = ((unsigned long)pfn_to_page(pfn + nr_pages)) - 1;
155 end = PAGE_ALIGN(end);
156 /* overlap check (because we have to align page */
157 list_for_each_entry(tmp, head, list) {
158 if (tmp->type != KCORE_VMEMMAP)
159 continue;
160 if (start < tmp->addr + tmp->size)
161 if (end > tmp->addr)
162 end = tmp->addr;
163 }
164 if (start < end) {
165 vmm = kmalloc(sizeof(*vmm), GFP_KERNEL);
166 if (!vmm)
167 return 0;
168 vmm->addr = start;
169 vmm->size = end - start;
170 vmm->type = KCORE_VMEMMAP;
171 list_add_tail(&vmm->list, head);
172 }
173 return 1;
174
175 }
176 #else
177 static int
get_sparsemem_vmemmap_info(struct kcore_list * ent,struct list_head * head)178 get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
179 {
180 return 1;
181 }
182
183 #endif
184
185 static int
kclist_add_private(unsigned long pfn,unsigned long nr_pages,void * arg)186 kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg)
187 {
188 struct list_head *head = (struct list_head *)arg;
189 struct kcore_list *ent;
190 struct page *p;
191
192 if (!pfn_valid(pfn))
193 return 1;
194
195 p = pfn_to_page(pfn);
196
197 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
198 if (!ent)
199 return -ENOMEM;
200 ent->addr = (unsigned long)page_to_virt(p);
201 ent->size = nr_pages << PAGE_SHIFT;
202
203 if (!virt_addr_valid(ent->addr))
204 goto free_out;
205
206 /* cut not-mapped area. ....from ppc-32 code. */
207 if (ULONG_MAX - ent->addr < ent->size)
208 ent->size = ULONG_MAX - ent->addr;
209
210 /*
211 * We've already checked virt_addr_valid so we know this address
212 * is a valid pointer, therefore we can check against it to determine
213 * if we need to trim
214 */
215 if (VMALLOC_START > ent->addr) {
216 if (VMALLOC_START - ent->addr < ent->size)
217 ent->size = VMALLOC_START - ent->addr;
218 }
219
220 ent->type = KCORE_RAM;
221 list_add_tail(&ent->list, head);
222
223 if (!get_sparsemem_vmemmap_info(ent, head)) {
224 list_del(&ent->list);
225 goto free_out;
226 }
227
228 return 0;
229 free_out:
230 kfree(ent);
231 return 1;
232 }
233
kcore_ram_list(struct list_head * list)234 static int kcore_ram_list(struct list_head *list)
235 {
236 int nid, ret;
237 unsigned long end_pfn;
238
239 /* Not inialized....update now */
240 /* find out "max pfn" */
241 end_pfn = 0;
242 for_each_node_state(nid, N_MEMORY) {
243 unsigned long node_end;
244 node_end = node_end_pfn(nid);
245 if (end_pfn < node_end)
246 end_pfn = node_end;
247 }
248 /* scan 0 to max_pfn */
249 ret = walk_system_ram_range(0, end_pfn, list, kclist_add_private);
250 if (ret)
251 return -ENOMEM;
252 return 0;
253 }
254 #endif /* CONFIG_HIGHMEM */
255
kcore_update_ram(void)256 static int kcore_update_ram(void)
257 {
258 LIST_HEAD(list);
259 LIST_HEAD(garbage);
260 int nphdr;
261 size_t phdrs_len, notes_len, data_offset;
262 struct kcore_list *tmp, *pos;
263 int ret = 0;
264
265 down_write(&kclist_lock);
266 if (!xchg(&kcore_need_update, 0))
267 goto out;
268
269 ret = kcore_ram_list(&list);
270 if (ret) {
271 /* Couldn't get the RAM list, try again next time. */
272 WRITE_ONCE(kcore_need_update, 1);
273 list_splice_tail(&list, &garbage);
274 goto out;
275 }
276
277 list_for_each_entry_safe(pos, tmp, &kclist_head, list) {
278 if (pos->type == KCORE_RAM || pos->type == KCORE_VMEMMAP)
279 list_move(&pos->list, &garbage);
280 }
281 list_splice_tail(&list, &kclist_head);
282
283 proc_root_kcore->size = get_kcore_size(&nphdr, &phdrs_len, ¬es_len,
284 &data_offset);
285
286 out:
287 up_write(&kclist_lock);
288 list_for_each_entry_safe(pos, tmp, &garbage, list) {
289 list_del(&pos->list);
290 kfree(pos);
291 }
292 return ret;
293 }
294
append_kcore_note(char * notes,size_t * i,const char * name,unsigned int type,const void * desc,size_t descsz)295 static void append_kcore_note(char *notes, size_t *i, const char *name,
296 unsigned int type, const void *desc,
297 size_t descsz)
298 {
299 struct elf_note *note = (struct elf_note *)¬es[*i];
300
301 note->n_namesz = strlen(name) + 1;
302 note->n_descsz = descsz;
303 note->n_type = type;
304 *i += sizeof(*note);
305 memcpy(¬es[*i], name, note->n_namesz);
306 *i = ALIGN(*i + note->n_namesz, 4);
307 memcpy(¬es[*i], desc, descsz);
308 *i = ALIGN(*i + descsz, 4);
309 }
310
311 static ssize_t
read_kcore(struct file * file,char __user * buffer,size_t buflen,loff_t * fpos)312 read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
313 {
314 char *buf = file->private_data;
315 size_t phdrs_offset, notes_offset, data_offset;
316 size_t phdrs_len, notes_len;
317 struct kcore_list *m;
318 size_t tsz;
319 int nphdr;
320 unsigned long start;
321 size_t orig_buflen = buflen;
322 int ret = 0;
323
324 down_read(&kclist_lock);
325
326 get_kcore_size(&nphdr, &phdrs_len, ¬es_len, &data_offset);
327 phdrs_offset = sizeof(struct elfhdr);
328 notes_offset = phdrs_offset + phdrs_len;
329
330 /* ELF file header. */
331 if (buflen && *fpos < sizeof(struct elfhdr)) {
332 struct elfhdr ehdr = {
333 .e_ident = {
334 [EI_MAG0] = ELFMAG0,
335 [EI_MAG1] = ELFMAG1,
336 [EI_MAG2] = ELFMAG2,
337 [EI_MAG3] = ELFMAG3,
338 [EI_CLASS] = ELF_CLASS,
339 [EI_DATA] = ELF_DATA,
340 [EI_VERSION] = EV_CURRENT,
341 [EI_OSABI] = ELF_OSABI,
342 },
343 .e_type = ET_CORE,
344 .e_machine = ELF_ARCH,
345 .e_version = EV_CURRENT,
346 .e_phoff = sizeof(struct elfhdr),
347 .e_flags = ELF_CORE_EFLAGS,
348 .e_ehsize = sizeof(struct elfhdr),
349 .e_phentsize = sizeof(struct elf_phdr),
350 .e_phnum = nphdr,
351 };
352
353 tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *fpos);
354 if (copy_to_user(buffer, (char *)&ehdr + *fpos, tsz)) {
355 ret = -EFAULT;
356 goto out;
357 }
358
359 buffer += tsz;
360 buflen -= tsz;
361 *fpos += tsz;
362 }
363
364 /* ELF program headers. */
365 if (buflen && *fpos < phdrs_offset + phdrs_len) {
366 struct elf_phdr *phdrs, *phdr;
367
368 phdrs = kzalloc(phdrs_len, GFP_KERNEL);
369 if (!phdrs) {
370 ret = -ENOMEM;
371 goto out;
372 }
373
374 phdrs[0].p_type = PT_NOTE;
375 phdrs[0].p_offset = notes_offset;
376 phdrs[0].p_filesz = notes_len;
377
378 phdr = &phdrs[1];
379 list_for_each_entry(m, &kclist_head, list) {
380 phdr->p_type = PT_LOAD;
381 phdr->p_flags = PF_R | PF_W | PF_X;
382 phdr->p_offset = kc_vaddr_to_offset(m->addr) + data_offset;
383 if (m->type == KCORE_REMAP)
384 phdr->p_vaddr = (size_t)m->vaddr;
385 else
386 phdr->p_vaddr = (size_t)m->addr;
387 if (m->type == KCORE_RAM || m->type == KCORE_REMAP)
388 phdr->p_paddr = __pa(m->addr);
389 else if (m->type == KCORE_TEXT)
390 phdr->p_paddr = __pa_symbol(m->addr);
391 else
392 phdr->p_paddr = (elf_addr_t)-1;
393 phdr->p_filesz = phdr->p_memsz = m->size;
394 phdr->p_align = PAGE_SIZE;
395 phdr++;
396 }
397
398 tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *fpos);
399 if (copy_to_user(buffer, (char *)phdrs + *fpos - phdrs_offset,
400 tsz)) {
401 kfree(phdrs);
402 ret = -EFAULT;
403 goto out;
404 }
405 kfree(phdrs);
406
407 buffer += tsz;
408 buflen -= tsz;
409 *fpos += tsz;
410 }
411
412 /* ELF note segment. */
413 if (buflen && *fpos < notes_offset + notes_len) {
414 struct elf_prstatus prstatus = {};
415 struct elf_prpsinfo prpsinfo = {
416 .pr_sname = 'R',
417 .pr_fname = "vmlinux",
418 };
419 char *notes;
420 size_t i = 0;
421
422 strlcpy(prpsinfo.pr_psargs, saved_command_line,
423 sizeof(prpsinfo.pr_psargs));
424
425 notes = kzalloc(notes_len, GFP_KERNEL);
426 if (!notes) {
427 ret = -ENOMEM;
428 goto out;
429 }
430
431 append_kcore_note(notes, &i, CORE_STR, NT_PRSTATUS, &prstatus,
432 sizeof(prstatus));
433 append_kcore_note(notes, &i, CORE_STR, NT_PRPSINFO, &prpsinfo,
434 sizeof(prpsinfo));
435 append_kcore_note(notes, &i, CORE_STR, NT_TASKSTRUCT, current,
436 arch_task_struct_size);
437 /*
438 * vmcoreinfo_size is mostly constant after init time, but it
439 * can be changed by crash_save_vmcoreinfo(). Racing here with a
440 * panic on another CPU before the machine goes down is insanely
441 * unlikely, but it's better to not leave potential buffer
442 * overflows lying around, regardless.
443 */
444 append_kcore_note(notes, &i, VMCOREINFO_NOTE_NAME, 0,
445 vmcoreinfo_data,
446 min(vmcoreinfo_size, notes_len - i));
447
448 tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos);
449 if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) {
450 kfree(notes);
451 ret = -EFAULT;
452 goto out;
453 }
454 kfree(notes);
455
456 buffer += tsz;
457 buflen -= tsz;
458 *fpos += tsz;
459 }
460
461 /*
462 * Check to see if our file offset matches with any of
463 * the addresses in the elf_phdr on our list.
464 */
465 start = kc_offset_to_vaddr(*fpos - data_offset);
466 if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
467 tsz = buflen;
468
469 m = NULL;
470 while (buflen) {
471 /*
472 * If this is the first iteration or the address is not within
473 * the previous entry, search for a matching entry.
474 */
475 if (!m || start < m->addr || start >= m->addr + m->size) {
476 list_for_each_entry(m, &kclist_head, list) {
477 if (start >= m->addr &&
478 start < m->addr + m->size)
479 break;
480 }
481 }
482
483 if (&m->list == &kclist_head) {
484 if (clear_user(buffer, tsz)) {
485 ret = -EFAULT;
486 goto out;
487 }
488 m = NULL; /* skip the list anchor */
489 } else if (!pfn_is_ram(__pa(start) >> PAGE_SHIFT)) {
490 if (clear_user(buffer, tsz)) {
491 ret = -EFAULT;
492 goto out;
493 }
494 } else if (m->type == KCORE_VMALLOC) {
495 vread(buf, (char *)start, tsz);
496 /* we have to zero-fill user buffer even if no read */
497 if (copy_to_user(buffer, buf, tsz)) {
498 ret = -EFAULT;
499 goto out;
500 }
501 } else if (m->type == KCORE_USER) {
502 /* User page is handled prior to normal kernel page: */
503 if (copy_to_user(buffer, (char *)start, tsz)) {
504 ret = -EFAULT;
505 goto out;
506 }
507 } else {
508 if (kern_addr_valid(start)) {
509 /*
510 * Using bounce buffer to bypass the
511 * hardened user copy kernel text checks.
512 */
513 if (copy_from_kernel_nofault(buf, (void *)start,
514 tsz)) {
515 if (clear_user(buffer, tsz)) {
516 ret = -EFAULT;
517 goto out;
518 }
519 } else {
520 if (copy_to_user(buffer, buf, tsz)) {
521 ret = -EFAULT;
522 goto out;
523 }
524 }
525 } else {
526 if (clear_user(buffer, tsz)) {
527 ret = -EFAULT;
528 goto out;
529 }
530 }
531 }
532 buflen -= tsz;
533 *fpos += tsz;
534 buffer += tsz;
535 start += tsz;
536 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
537 }
538
539 out:
540 up_read(&kclist_lock);
541 if (ret)
542 return ret;
543 return orig_buflen - buflen;
544 }
545
open_kcore(struct inode * inode,struct file * filp)546 static int open_kcore(struct inode *inode, struct file *filp)
547 {
548 int ret = security_locked_down(LOCKDOWN_KCORE);
549
550 if (!capable(CAP_SYS_RAWIO))
551 return -EPERM;
552
553 if (ret)
554 return ret;
555
556 filp->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
557 if (!filp->private_data)
558 return -ENOMEM;
559
560 if (kcore_need_update)
561 kcore_update_ram();
562 if (i_size_read(inode) != proc_root_kcore->size) {
563 inode_lock(inode);
564 i_size_write(inode, proc_root_kcore->size);
565 inode_unlock(inode);
566 }
567 return 0;
568 }
569
release_kcore(struct inode * inode,struct file * file)570 static int release_kcore(struct inode *inode, struct file *file)
571 {
572 kfree(file->private_data);
573 return 0;
574 }
575
576 static const struct proc_ops kcore_proc_ops = {
577 .proc_read = read_kcore,
578 .proc_open = open_kcore,
579 .proc_release = release_kcore,
580 .proc_lseek = default_llseek,
581 };
582
583 /* just remember that we have to update kcore */
kcore_callback(struct notifier_block * self,unsigned long action,void * arg)584 static int __meminit kcore_callback(struct notifier_block *self,
585 unsigned long action, void *arg)
586 {
587 switch (action) {
588 case MEM_ONLINE:
589 case MEM_OFFLINE:
590 kcore_need_update = 1;
591 break;
592 }
593 return NOTIFY_OK;
594 }
595
596 static struct notifier_block kcore_callback_nb __meminitdata = {
597 .notifier_call = kcore_callback,
598 .priority = 0,
599 };
600
601 static struct kcore_list kcore_vmalloc;
602
603 #ifdef CONFIG_ARCH_PROC_KCORE_TEXT
604 static struct kcore_list kcore_text;
605 /*
606 * If defined, special segment is used for mapping kernel text instead of
607 * direct-map area. We need to create special TEXT section.
608 */
proc_kcore_text_init(void)609 static void __init proc_kcore_text_init(void)
610 {
611 kclist_add(&kcore_text, _text, _end - _text, KCORE_TEXT);
612 }
613 #else
proc_kcore_text_init(void)614 static void __init proc_kcore_text_init(void)
615 {
616 }
617 #endif
618
619 #if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
620 /*
621 * MODULES_VADDR has no intersection with VMALLOC_ADDR.
622 */
623 static struct kcore_list kcore_modules;
add_modules_range(void)624 static void __init add_modules_range(void)
625 {
626 if (MODULES_VADDR != VMALLOC_START && MODULES_END != VMALLOC_END) {
627 kclist_add(&kcore_modules, (void *)MODULES_VADDR,
628 MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
629 }
630 }
631 #else
add_modules_range(void)632 static void __init add_modules_range(void)
633 {
634 }
635 #endif
636
proc_kcore_init(void)637 static int __init proc_kcore_init(void)
638 {
639 proc_root_kcore = proc_create("kcore", S_IRUSR, NULL, &kcore_proc_ops);
640 if (!proc_root_kcore) {
641 pr_err("couldn't create /proc/kcore\n");
642 return 0; /* Always returns 0. */
643 }
644 /* Store text area if it's special */
645 proc_kcore_text_init();
646 /* Store vmalloc area */
647 kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
648 VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
649 add_modules_range();
650 /* Store direct-map area from physical memory map */
651 kcore_update_ram();
652 register_hotmemory_notifier(&kcore_callback_nb);
653
654 return 0;
655 }
656 fs_initcall(proc_kcore_init);
657